AM. ZOOLOGIST, 7:357-363 (1967).

Wolf Socialization: A Study of Temperament in a Wild

Social Species

JEROME H. WOOLPY AND BENSON E. GINSBURG

Behavior Genetics Laboratory, University of Chicago, IllinoisSYNOPSIS. A detailed analysis was made of the process by which the wolf comes from a state of

unfamiliarity and fear of humans to a state of familiarity and friendliness. The nature of theprocess was found to depend on the age of the animal as well as the technique employed by theexperimenter. Although young cubs were found to respond positively to almost any form ofhuman contact, the older cubs and juveniles required much more time and effort to socialize,and fully matured adults offered very special problems which required specialized techniques toovercome. Periods beyond which no socialization could occur were not found. Wolves socializedas cubs had to be reinforced repeatedly in order to maintain their social bond with humans;however, adult wolves retained their socialized behavior even after being left with unsocializedanimals and not handled for 18-22 months. Wolves socialized with the aid of tranquilizingdrugs (chlorpromazine, librium, and reserpine) did not retain their socialization when the drugswere withdrawn on a variety of schedules. The development of fear responses as the animalsgrow older, and the association of fear with the unfamiliar, closely parallel the increasing diffi-culty of acquiring socialized behavior as well as the decreasing difficulty of retaining that be-havior once it is acquired. Socialization is viewed as a conditioning process which must takeplace after the development and in the presence of the free expression of the subjective com-ponents of fear, a separable aspect of the general phenomenon of genetic wildness.

The evolution of social behavior andthe mechanisms by means of which it de-velops and is maintained have becomemajor areas of investigation not only forzoologists and naturalists, but also forpsychologists interested in the formation ofsocial bonds, and anthropologists inter-ested in the biological origins of humangroup behavior. While many of the recentinvestigations have dealt largely with pri-mates, those aspects of non-human primatebehavior that may be considered as spe-cialized and unique can only be identifiedin the context of comparative studies withsocial species in other mammalian groups.Among these, the wolf serves as an excellentexample, being, as it is, a highly socialspecies that has been studied in the wild(Murie, 1944; Crisler, 1958; Mech, 1966);under semi-natural conditions of confine-ment (Schenkel, 1948; Rabb, Ginsburg,and Andrews, 1962; Ginsburg, 1965, 1967;Rabb, Woolpy, and Ginsburg, 1967); andunder conditions of domestication (Fen-tress, 1967).

The present study derives from our inter-t est in genetic wildness and emotionality in

relation to the formation of social bondsin mammals (Ginsburg and Allee, 1942;

Ginsburg, 1949, 1958) and more directlyfrom our 8-year study of the social organi-zation of a captive wolf pack (Rabb, Gins-burg, and Andrews, 1962; Ginsburg, 1965,1967; Rabb, Woolpy, and Ginsburg, 1967),supplemented by additional studies on theinteractions of wolves and humans (Gins-burg, Woolpy, Kleiman, and Edwards,1962). During the course of these studieswe have analyzed the behavior of thewolf from the standpoint of the devel-opment and maintenance of social rela-tionships between wolves and wolves, aswell as between wolves and humans.We have called the process by whichthese wolf-human relationships develop,"socializaticjn." It is most simply char-acterized by the change in the be-havior which a human elicits from awolf. The wolf comes from an unsocial-ized state of avoidance or negative responsetoward humans to a socialized state ofapproach and positive response towardsthem.

We have been primarily concerned withthe effects of various experimental pro-cedures on the process of a developing wolf-human social relationship. The socializa-tion process has been studied in relation

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to the behavioral ontogeny of the wolf."By subjecting wolves to human handlingbefore, during, and after the manifestationof the autonomic and skeletal motor re-sponses associated with the expression offear, we have attempted to test and eluci-

vdate the hypothesis that the principal ob-stacle to the acquisition of positive socialresponses to humans is the wolf's fear ofthe experimenter; and that this fear, withits attendant emotionality and avoidance,is a separable and essential aspect of thegeneral phenomenon of genetic wildness(Ginsburg, 1965, 1967).

Both the acquisition and retention ofpositive social behavior towards humanshave been tested at various ages beforeand after the development of overt fearresponses in order to determine if the on-set of fear had any pervasive disruptiveeffects on previously acquired socialization.In addition, we have attempted to blockor reduce fear by means of tranquilizingdrugs and to condition wolves to humanhandling under tranquilization as well aswithout the aid of drugs.

The present report is based on sevenwolves with various histories of socializa-tion to humans. Three^ were exposed tohuman handling continuously from birth.Three others were handled during the in-fant and juvenile periods and subsequentlyplaced with unhandled animals for 18 to 22months, and one_ had_ had_no direct humancontact until she was approximately fiveyears old.

Animals that were deprived of direct hu-man contact were maintained with orwithout other wolves in indoor-outdoorruns which were cleaned manually everyday. They were fed meat placed on thefloor of the run by hand. In two instancesthe deprived animals were maintained atthe zoo. Animals on a handling schedulewere housed and fed in the same manneras the deprived animals.

The socialization procedure was designedto offer the wolf the maximum possiblelatitude of response to the experimenterwhile at the same time permitting the in-vestigator to employ a variety of tech-

niques. After acclimatization to laboratorysurroundings, including the presence ofthe experimenter outside the pen, the ex-perimental animal was confined to the in-side portion of his run (4' X 8') for severalhours prior to the handling session, aswell as during the period of handling. Ananimal was judged to be acclimatized whenit moved freely about its run and showedno obvious autonomic signs (salivation,piloerection, urination, defecation, pupil-lary dilation, and trembling) or posturalattitudes associated with fear while theexperimenter was present in the roomoutside the run. The investigator wouldthen enter the run, seat himself on thefloor against the partition dividing the runfrom the room, and remain there quietly.The autonomic and postural signs wouldagain be evoked. When the animal becamehabituated to the presence of the experi-menter just inside the pen, these signs againsubsided, and the investigator would thenbegin to move his body, maintaining asitting position, reach out with his hand,and finally, after a period of weeks ormonths, initiate physical contact. At each

" new phase the autonomic and posturalsigns described would again appear to vary-ing degrees, and the wolf would be judgedto be ready for the next phase when thesesigns again abated (see description of pro-cedure in Ginsburg, 1965, pp. 61-65).

Observations of the wolves' behavior dur-ing the socialization sessions were inde-pendently recorded by the experimenterand another member of the research team.Film records for later analysis were madeon a sampling basis.

In wolf cubs born in captivity, the firstsign of the development of fear is cautious-ness in approach on initial contact with aperson or strange object. This behavioris exhibited by the .sjxth or seventh weekof life. Prior to this time, the cubs tend toapproach anyone readily, or at least notto move away from them. Their approachesare characterized by tail-wagging, nosing,licking, and biting, and are noticeablyvariable among littermates. Subsequent tothe first overt signs of fear, it becomes pro-

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gressively more time-consuming to obtaina positive response from a cub on initialcontact. By the end of the eighth weeksuch responses usually are not elicited ina single session unless it is unusually pro-longed. Toward the end of the third monththe fear responses are developed to thepoint where strange objects, loud noises,or strange people usually elicit urination,defecation, salivation, crouching, piloerec-tion, pupillary ̂ dilation, tail-tucking* trem-bling, and a laying back of the ears (fordescriptions of characteristic postural atti-tudes of the wolf, see Schenkel, 1948). Fromthis time on, socialization of previously un-socialized cubs requires considerable timeand effort. At six months the process ofsocialization takes still longer to achieve,while the fully adult animal requires evenlonger to become socialized to humanhandling.

Wolves are highly social in nature(Murie, 1944; Crisler, 1958; Mech, 1966),as well as under conditions of confinementwhen in groups (Rabb, Ginsburg, andAndrews, 1962; also Rabb, et al, this vol-ume). Once socialized, they are extremelygregarious to humans and exhibit all ofthe attitudes and mannerisms of a veryfriendly dog, as well as some ()i those seenin most wolves, but not usually observedin dogs. These include attempts to holdthe investigator with their paws, and amouthing of the chin and lower facearea (Fig. 1).

Socialization in the adult wolf underthe conditions obtaining in our laboratorytakes place in four gradual but definablestages: escape, avoidance, approach-aggres-sion, and finally the friendly or socializedstate.

During the initial phase of socialization,the unsocialized adult wolf, that has be-come acclimated to its surroundings andto the experimenter's presence outside thepen, becomes highly emotional when theexperimenter enters the run. Such an ani-mal usually attempts various escape ma-neuvers, including digging at the concretefloor, pawing at the closed doors, andjumping high into the air. As the wolf

FIG. 1. Muzzle-bite greeting by socialized wolf.

becomes somewhat more acclimated, thisbehavior alternates with an extreme re-treat in which the wolf crouches in thecorner of the run farthest from the ob-server with his tail tucked between his legsand his ears back, panting, trembling, andsalivating. This extremely fearful be-havior is accompanied by frequent defeca-tion and urination, trembling, and changesin pupillary diameter. This first stage iscalled the escape stage of the socializationprocess.

Depending on the age and previous ex-perience of the wolf, the second or avoid-ance stage will be exhibited approximatelya month after the handling sessions begin.This stage differentiates slowly out of theescape phase. The intensity of the emotion-ality as judged by the autonomic signsbegins to abate, and the wolf's attempts atactive escape are less frequent. Now hesimply stays as far away from the experi-menter as he can. However, instead ofcrouching and trembling in the corner, thewolf will sit in a more relaxed manner and

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may untuck his tail from between his legsand point his ears straight up and towardthe experimenter. Should the experimenterincrease his own bodily movements duringthe early phases of his second stage, thewolf may revert to previous emotionalitiyand escape behavior. Usually, after severalmonths the wolf consistently permits theexperimenter's approach, and it is at thisstage that the handling may begin. Associalization progresses, the wolf makesincipient movements toward the experi-menter, which can be stopped if the experi-menter shifts his eyes and looks directly atthe wolf.

Soon afterwards the approach stage, be-gins. This represents a critical and delicatestage of the socialization process. Thewolf is at first investigative and highlyalert. He will sniff timidly at the experi-menter's body and clothing, but will retreatif the experimenter moves or looks directlyat him. Later, during the approach stage,he will attempt to chew and pull the ex-perimenter's clothing, and will rub in thearea where the experimenter was sitting, assoon as the latter has left the run. Occa-sionally he will also mark this area withurine. He will next rub against the experi-menter himself, and occasionally micturatedirectly on him (a pattern of behavior moreoften exhibited in coyotes than in wolves).While rubbing against the handler, hewill often allow himself to be petted with-out retreating.

As the wolf's familiarity with the ex-perimenter increases, he begins to takemore liberties. This is enhanced if pro-tective clothing is worn under the usuallaboratory coat or coveralls. The wolf mayattack such devices as though they werenot a part of the investigator. Generally,the biting and tugging is directed at thehandler's clothing. If one tries to preventthis, the wolf may bite harder and snapmore vigorously. Attempts to dominatethe animal physically at this stage mayeither lead to a full blown attack or mayprovide a setback to an earlier stage ofsocialization that is then more difficult toovercome than the first time it was en-

countered. In practice, we have foundthat it is best to suppress one's physicalmovements when under mild attack. In-variably the animals retreat if a secondmember of the team approaches or entersthe run. The handler is, therefore, in noreal danger.

As it is difficult to keep the wolf ap-proaching and at the same time preventhim from biting, the experimenter at-tempts to change the oral investigativebehavior of the wolf into something moreacceptable by petting and scratching him.Fortunately, the wolf will threaten whenhe is antagonized, and thus give amplewarning of his intention. Usually thethreat is ambivalent, consisting of a slightcurl of the upper lip which just exposesthe teeth. This may be accompanied bya low growl. The ears are in a naturalupright position or slanted slightly out tothe side, and the tail is in the normal posi-tion—down and slightly out. At this pointthe experimenter must inhibit the aggres-sion to the point where the threat is with-drawn and the posture of the wolf returnsto near normal. If he is not successful inthis attempt, he must rely on the approachof a colleague in order to make the wolfwithdraw, or he must leave the run beforethe threat turns to attack. If he frightensthe wolf, the socialization process may haveto be considerably extended. If he doesnot sufficiently inhibit the wolf, he maysustain a vigorous attack. If his retreat istoo hasty, the wolf is more inclined to beaggressive during the next encounter. Care-ful teamwork on the part of the experi-menters generally keeps these problems toa minimum.

The fourth and final stage of socializa-tion, during which the wolf becomes friend-ly, is exhibited when the experimenter is•Successful in preventing the wolf's aggres-sion without inhibiting his approach. At

"this stage the wolf is no longer fearful ofthe experimenter, approaching him readilyand assuming postural attitudes that invitescratching and rubbing. During this phaseit is likely that the wolf will begin to lickthe experimenter's hands and face. Still

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later he will begin to wag his tail whenthe experimenter enters the room and willput his front feet up on the door of therun in anticipation of the experimenter'sentry. The tail-wagging becomes more vig-orous as the experimenter approaches therun. At this point, some six or sevenmonths after the initial contact, the typicalwolf may be considered socialized. This isalso the stage at which the wolf will attemptto hold the experimenter with his pawsand to greet him by placing his jawsaround the chin and lower face in muchthe same way that he would place hismouth around the muzzle of another wolfin a wolf-wolf greeting ceremony.

Socialized behavior of the friendly sortis easily acquired by wolves socialized asyoung cubs and somewhat less readily byjuveniles. In several instances where suchsocialized young wolves have then beenisolated from further handling for ex-tended periods (over 6 months) the so-cialization was not retained. It appears,therefore, that in the young wolf this socialbehavior must continue to be reinforcedin order to prevent the fear responses fromsetting in. However, wolves exhibitingfully socialized behavior as adults have notbeen observed to revert, even after periodsexceeding a year during which they hadno direct human handling. These fullysocialized animals retain their friendly be-havior and generalize it to all humans whoact appropriately toward them. We havenever observed the one-mannishness so fre-quently seen in domestic dogs in any ofour seven socialized wolves, and we attrib-ute this to the extreme gregariousness ofthe wolf and to his ability to generalize, aquality which is differentially developed inthe many varieties of domestic dogs. Thenecessity of having to confine wolves in asmall number of runs in our laboratoryhas provided a physical situation in whichit was easily shown that in contrast to theability of adult wolves to generalize theirhuman socialization to all humans that actappropriately towards them, they do notgeneralize their wolf socialization to allwolves. Each new wolf-wolf Relationship,

which develops among cage-mates, requiresa few weeks of intensified social interaction,including fighting, to become established.However, once it is established it remainsso throughout periods of separation of atleast one year. These permanent relation-ships have not been observed among ani-mals younger than one year.

So far as the socialization procedure isconcerned, handling sessions lasting 10-20min were found to be as effective as thoselasting for an hour or more. Intersession'intervals of three days were as effective asdaily sessions, and once the extreme re-actions of fear had been overcome, occa-sional intervals lasting several weeks werefound to stimulate the wolf to approachmore readily. Socialization sessions werenot as effective when there was more thanone wolf in the run, even if the secondwolf was fully socialized. Under these con-ditions the less-socialized wolf would oftenuse the other as a barrier behind whichhe could retreat and from which he couldmount aggressive attacks.

As mentioned earlier, a wolf socializedwhile very young must be reinforced in thissocialization if it is to persist, whereas onesocialized over the same period of timeinto adulthood will retain the socializationover a considerable period in which it isnot reinforced. However, those wolves thathave been socialized early and have beenso handled as to retain their socializationappear to be more intense in their positivesocial responses tMh the others.

Because of the critical role of the extremewariness of a wild animal in the process ofsocialization—a behavior that manifests it-self as an extremely low threshold of re-sponse to any environmental novelty, aswell as an intense and emotional responseof long duration to such novelty, we haveattempted to socialize wolves using librium(methaminodiazepoxide), reserpine (3,4,5-trimethoxybenzoyl methyl reserpate), andchlorpromazine (2-chlor-10-[3-dimethylami-nopropyl] phenothiazine). Doses were firstscreened on dogs of comparable bodyweight and were regulated to be just sub-ataxic on this basis. Doses were individual-

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ly prepared according to the body weightof each experimental animal and wereplaced in capsules which were administeredorally, usually disguised in small pieces ofmeat. A variety of dosages and dosage-in-tervals were used, and experiments duringwhich the investigators were aware of theprocedures were alternated with experi-ments in which some of the observers didnot know which, if any, of the animals hadbeen drugged.

The lowest dosage levels at which behav-ioral effects of previously untreated wolveswere noted were: librium, 5 mg/kg; chlor-promazine, 5 mg/kg; and reserpine, 0.08mg/kg. Despite the fact that the drugs inquestion are presumed to have differentmodes of action, their major behavioraleffects are comparable. At these dosage lev-els the partially socialized wolf increasedhis frequency of approach to the experi-menter and permitted the latter to ap-proach without trying to walk away. Thiseffect lasted from about the fourth throughthe eighth hours, with the peak effects ob-servable at approximately 6 hours afteroral administration.

The major effect of these tranquilizerson unsocialized and partially socializedwolves was a temporal compression of manyof the behaviors characterizing the firstthree stages of socialization, so that the en-tire process up to this point occurred overa period of approximately 4 days insteadof several months. During the approachphase the animals were more aggressivethan were those that were drug-free. Thedrugs also seemed to repress the threat pos-tures which normally forewarn the experi-menter of an impending attack. Thus, thetranquilized wolf may appear to be moreaggressive than his control, depending onthe time after administration of the dose,during which he is tested (varying aroundthe twelfth hour after administration).Both short-term and long-term tranquiliza-tion have thus far produced no lasting be-havioral effects after the drugs are with-drawn. Fully socialized wolves are notmarkedly affected by the drugs in their so-cial responses. When the tranquilizers men-tioned were administered as a single un-

repeated oral dose (at the lowest effectivelevels) the wolves exhibited a lower thresh-old for aggression over approximately twodays. Fifty percent greater doses producedthe same effects for slightly longer periodsof time and were accompanied, as may beexpected, by increased side effects which in-cluded sedation and varying degrees ofataxia. At present we are testing the effectof daily doses of librium over a prolongedperiod (8 months at this writing) and havefound that the amount of drug necessaryto produce any noticeable effect is overthree times that which is effective as a sin-gle dose in an unhabituated animal (15mg/kg). Furthermore, on none of the regi-mens of daily dosage have we found anycycling of behavior. The wolf is simplymore likely to approach the experimenterat any time. Also, at this dose there havebeen very few incidents of aggression.

The approach responses exhibited undertranquilization do not involve the tail-wagging, mouthing, and other expressionsseen in fully socialized control animals. Thewolves seem to be brought to the somewhatambivalent approach stage consequentupon the reduction of fear, and maintainedthere—depending on the dose and intervalof drug administration used. Thus far wehave not been able to bring any animal tothe fully socialized stage under drug or tomaintain it at the most positive approachstage achieved under drug after the drughas been withdrawn, regardless of the vari-ations in the tapering-off process. The tran-quilizers somewhat mimic the transitionfrom avoidance to approach stages in con-trol animals (it should be noted that in allof these experiments each animal served asits own control), thereby lending credenceto the idea that loss of fear is the essentialstep in the process of socialization. Further-more, since the drug does not affect the so-cial behavior of the socialized wolf, it doesnot by itself induce approach or aggression,but it reduces fear. In so doing, it preventsan animal that has still not been positivelysocialized from having his subjective fearresponses conditioned. Thus, blocking offear is not conducive to socialization.

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SUMMARY

Fundamentally, the wolf is a social ani-mal, having the capacity to form lastingsocial relationships and to live in rather ex-clusive packs with 10 or 20 of his own kind.Generally, these relationships are formedvery early in life and nurtured by constantwolf-wolf contact throughout at least thefirst year. Consistent with the exclusivityof the pack is the fact that new social rela-tionships are formed with difficulty, wheth-er these are between wolf and wolf or be-tween wolf and human. The exclusivityand solidity of the pack are maintained inpart by the mechanism of fear of the un-familiar, which is characteristic of wildness.This fear can be reduced chemically, butsuch reduction does not by itself induce theformation of lasting social relationships.These must be formed over a long periodif they are to be lasting, and one aspect oftheir formation appears to be coping withthe unreduced subjective fear response.While this response develops during thefirst three months, social relationships donot become permanently bonded for amuch longer time. The subjective affectivecomponent of the fear response which isassociated with the unfamiliar, appears tocontinue to develop over the entire firstyear. The socalization experiments bothwith and without the use of tranquilizingdrugs, as interpreted in the context of thedevelopment of wolf-wolf relationships be-tween individuals in a captive pack, lead usto conclude that permanent socialization isachieved only by the conditioning, throughexperience, of the subjective aspects of thefear response. Socialization is possible atany age, provided that the affective compo-nents of fear can be brought under control,either by means of artificial conditioningsuch as the kind we have described, or bymeans of its natural equivalent—continuedexperience in a wolf pack.

ACKNOWLEDGMENTS

The work reported here was supported by US-

PHS Grant MY-03361. The authors also gratefullyacknowledge the assistance, animals, and facilitiesprovided by Dr. George B. Rabb and the ChicagoZoological Park.

In addition to the authors, the wolves were han-dled by F. Miller, D. Kleiman, and C. Edwards.

Tranquilizing drugs were furnished by courtesyof the manufacturers as follows: librium, Hoffmann-La Roche; reserpine, CIBA: chlorpromazine, Smith,Kline, and French.

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